Manufacture of tanning substances



Patented a... 12, 1926.

orro Roam, or DARMSTADT, GERMANY.

MANUFACTURE TANNING SUBSTANCES.

Ho Drawing.

T 0 all whom it may concern:

Be it known that I, O'r'ro RoHM, doctor of philosophy director, a citizen of the German Republic, residing at Darmstadt, Germany, have invented certain new and useful Improvements in the lVIanufacture of Tanning Substances, of w hich the following is a specification.

My invention relates to an improved tanning method and more particularly to a new and useful tanning liquor or substance example, two offthe three ticular I have found and the process of manufacturing the same,

the essential constituents of the latter being an iron salt, an alkali metal silicate and sul lite cellulose liquor.

Invmanufacturing the tanning substance or liquor according to. my invention I em ploythe three ingredients either in aliqui'd orm or in a dry state. In the'former case I mix in the proportions required a solution of an iron salt with. a solution of an alkali metal silicate and a more or less diluted sulfite cellulose liquor in order to obtain a tanning liquor of suitable com osition, and in the latter case I! mix the 'ry or dried substances together the mixture in a suitable solvent. In some cases it may be advisable to employ, for substances in a dry state and to dissolve them, after they have been intimately mixed together, in the third substance which is in the form of a solution of appropriate concentration.

In employing a thus prepared liquor for tanning purposes, the hides or skins may be treated therewith in any suitable manner and in accordance with any appropriate operations' hitherto known in the art. In arhides and skins can be profitably treated with my improved tanning liquor and heavy leather of best quality can be produoed thereby. A particular advantage further resides in the fact that the tanning operation ensures good weight which is mainly due to a high proportion of iron oxid and silicic acid retained in the leather. The latter is of a grainy structure and of a light brown colour similar to that of oakbark tanned sole-leather. The colour is lighter and more uniform than in cases where iron salt and sulfite cellulose liquor alone are used for tanning purposes. Evidently the presence of sllicic acid has a clearing and filling efi'ect.

It has been suggested heretofore to proand dissolye that especially t ick' Application filed Marcht, 1924. Serial No. 697,155.

duce so -called iron leather by tanning the.

hides or skins with the aid of iron oxid or iron salts containing a strong acid, and

sulfite cellulose liquor, and to carry out the tanning process either in a single operation by treating the skins and hides with a mixture of the iron compound and the liquor, or in two operations by treating the same first with the iron compound and subseqyiently with the liquor. Further it has been recommended heretofore to employ for nning purposes sulfite cellulose liquor mixed with substances other than iron compounds. Furthermore it has been-suggested some time ago to use iron silicate for tanning purposes,v H r In contradistinction to the PIIOI' art, my

invention contemplates the new idea of employing a tanning liquor containing three well defined ingredients, that is to say, an iron compound or compounds, a silicate or silicates and sulfite cellulose liquor or, in other'words, an-iron salt solution, a silicate solution and sulfite cellulose liquor and, accordingly, my improved tanning therein, for the first time, the aforesaid three. ingredients or constituents are united in a suitable manner and with the result of ensuring thereby certain new and important advantages over the old state of the art. Apart from the aforestated advantages of my method of producing leather of suerior qualities, it has been found that the (defects of the methods of tanning hides and skins with the aid of iron solutions, as hitherto suggested or practiced, are entirely remedied by my new method. A further 95 advantage thereof, moreover, resides in the fact that'the tanning liquor prepared in accordance with my invention is of pracmethod is in prlnciple novel inasmuch as tically imperishable nature and further,

that the percentage of iron silicate therein may be increased to a relatively high degree without the occurrence tion.

In carrying out my method of making a tanning liquor and of treating hides and skins with such liquor I proceed in. a preferable Way as follows:

I add to 50 kg. of sulfite cellulose liquor of 20 B., 20 kg., of a 50% solution of iron chloride and a solution of 25 kg. waterglass of 36 B. in 125 litres ofwater. The solution thus obtained is sufiicient for tanning kg. of cowhides which are soaked ing, thus accomplished,

therein and dressed for about three days in a suitable dressing trough.

The tanning operation, properly speak- .and sulfite cellulose liquor, substantially as described.

2. The method of manufacturing a tanning liquor, consisting in mixing together a solution of an iron compound or compounds, a solution of an alkali metal silicate or silicates and sulfite cellulose liquor, substantially as described.

3. The method of manufacturing a tanning liquor consisting in mixing together an iron compound or compounds, an alkali metal silicate or silicates and dry sulfite celthe hides are washed lulose liquor, and dissolving the mixture in a suitable solvent, substantially as described.

4. A tanning substance consisting of an iron compound or compounds, an alkali metal silicate or silicates and dried sulliucellulose liquor mixed together in the pmportions required for the purpose.

5. A tanning liquor consisting of an iron compound or compounds, an alkali metal silicate or silicates and sulfitc cellulose liquor-mixed and dissolved in water in llaproportions required for the purpose.

6. The methodof manufacturing a tan ning substance, consisting in mixing to gether a solution of iron'chloride, a solution of water-glass and sulfite cellulose liquor.

T. A tanning substance, consisting of iron chloride, water-glass and sulfite CQlllllUM'. liquor.

In testimony whereof I affix my signature.

- o'r ro Roma. 

